Automatic control systems have been developed for automobiles, aircraft, ships and even some passenger trains. The development of automatic control systems for freight trains has encountered a number of problems arising from characteristics specifically associated with freight trains. Freight trains can be very long and the train may be subject to several different conditions of grade, curvature, speed restriction and aerodynamic drag along its length. As well the driver cannot be expected to remain cognisant of all these conditions. Another problem is that the train can be configured with at least as many different load mix configurations as the number of rail wagons. Load configurations change the dynamic characteristics of the train and therefore change the requirements for driving practice or train control.
One possible solution is to modify braking and couplings to improve the dynamic behaviour of trains. However most freight train operators usually have a large rolling stock base and modifying each of the train vehicles would introduce compatibility and logistic problems and require considerable expenditure. For these reasons extensive modification of rolling stock is generally resisted by freight train operators.
Another approach has been the development of control systems for trains such as those disclosed in Japanese patent 58075410 and U.S. Pat. No. 5,239,472. These systems are primarily concerned with minimizing energy usage and compliance with speed restrictions and signals. These control systems however are limited to suburban passenger trains rather than long freight trains. These systems do not take into account the variability of loading and length that characterizes freight trains.
A system that determines the train and track conditions and processes the information in conjunction with train restraint conditions and optimal operating parameters to provide optimum driving parameters is disclosed in U.S. Pat. No. 6,144,901. While considering a number of parameters the system described in U.S. Pat. No. 6,144,901 does not address all the particular characteristics of long freight trains as discussed above.